LC-MS/MS and immuno-electron subtyping combined with genetics show that OSMR mutations cause amyloid deposition of keratins 5/14 in familial primary localized cutaneous amyloidosis

Primary localized cutaneous amyloidosis (PLCA; MIM_105250) is a localized form of amyloidosis occurring exclusively in the skin, but the identity of the causal fibril protein still remains controversy. The aim of this study was to clarify the biochemical nature of PLCA-related amyloid and its underlying molecular basis by combining immunohistochemistry, immuno-electron microscopy, liquid chromatography-tandem mass spectrometry analysis (LMD-MS/MS) of microdissected cutaneous amyloid deposits with complete genetic analysis.